Minimum Distortion Point Tracking: Optimal Phase Shifting for Input- or Output-Parallel Connected DC-DC Converters

This paper introduces the notion of minimum distortion point tracking (MDPT): a control paradigm for input- or output-parallel connected dc-dc converters where switching waveforms are optimally phase shifted to minimize the total dc-bus ripple power. In a sense, MDPT generalizes the ubiquitous concept of interleaving in balanced multiphase dc-dc converters to a broad class of asymmetric input- or output-parallel connected dc-dc converters. Realizing power-quality improvement with control design implies that a drastic reduction in passive input or output filters can be achieved. This paper presents the mathematical characterization of the minimum distortion point (MDP) and a technique for MDPT. An experimental case study for three 600 W dc-dc converters demonstrates a 3× reduction in the bus voltage ripple, convergence to a static MDP in 40 ms, and the ability to dynamically track a time-varying MDP.